Figure 7.

Mechanism of the charge-enhanced or hydrophobicity-enhanced Spy variants in preventing client aggregation. For fast-aggregating clients (upper panel), both WT Spy and the charge-enhanced variants are capable of rapidly binding unfolded clients, but the latter also releases the substrate more slowly, resulting in very few aggregates. In contrast, although the hydrophobicity-enhanced variants are capable of forming tighter complexes with clients, their slow association rates limit their ability to prevent rapid aggregation. For slow-aggregating clients (lower panel), the very slow dissociation rates of the hydrophobicity-enhanced variants make up for their shortage in recognizing clients, resulting in almost equally holding activities as the charge-enhanced variants. Boxed regions indicate the processes more impactful in determining the aggregation of different types of clients.